1. Field of the Invention
The present invention relates to storage area networks (SANs) and more specifically to the isolation of inter-integrated circuit buses (I2C buses) in a multiple power domain environment.
2. Description of Related Art
In a SAN environment, storage devices such as digital linear tapes (DLTs) and redundant array of independent disks (RAID arrays) are connected to many kinds of servers via a high-speed interconnection such as Fibre Channel. Standard for Fibre Channel was developed, by the American National Standards Institute (ANSI) in the early 1990s specifically as a means to transfer large amounts of data very fast. The Fibre Channel standard can be used for copper cabling or fiber-optic cable at distances of up to 10 kilometers.
In a typical situation, SANs based on the Fibre Channel standard may be initially implemented as a group of server systems and storage devices connected by Fibre Channel adapters to a network. As the SAN grows, hubs and switches can be incorporated. The Fibre Channel standard supports several configurations including point-to-point and switched topologies. In a SAN environment, the Fibre Channel Arbitrated Loop (FC-AL) is used most often to create this high-speed storage network due to its inherent ability to deliver any-to-any connectivity among storage devices and servers. A FC-AL configuration consists of several components including servers, storage devices, and a Fibre Channel switch or hub.
The FC-AL provides not only a high-speed interconnection among storage devices but also strong reliability. In fact, several devices can be removed from the loop without any interruption to the data flow. Also, packets sent over a FC-AL are error-checked and packets can be re-transmitted if any are lost or corrupted. More information regarding SANs and Fibre Channel is provided in an article entitled xe2x80x9cStorage Area Networksxe2x80x9d from NetworkMagazine.com, the entirety of which is incorporated herein.
RAID arrays and JBODs are housed in disk enclosures. Devices within disk enclosures (e.g., repeaters, enclosure controllers, backplane controllers, memory devices, temperature sensors, port bypass circuits, disk drives, and fans) run off power supplies. From time to time, such power supplies may fail, thus halting the operation of the other devices within the disk enclosures. What is needed is a disk enclosure with a power scheme with great redundancy.
A disk enclosure includes (1) a first group of one or more power sources implementing a first power domain, (2) a first plurality of elements powered by the first group of power sources, (3) a second group of one or more power sources implementing a second power domain, and (4) a second plurality of elements powered by the second group of power sources. The disk enclosure also includes a first voltage circuit and a second voltage circuit each coupled to the first group of power sources and the second group of power sources. The first voltage circuit powers a third plurality of element while the second voltage circuit powers a fourth plurality of elements.